1. Field of the Invention
The present invention relates to an ink jet printing apparatus that includes a cap for covering the ink ejection ports of a print head.
2. Description of the Related Art
For an ink jet printing apparatus that prints an image by employing an ink ejection print head, a recovery process, such as a suction-based recovery procedure or a preliminary ejection procedure, is performed for the print head in order to maintain a satisfactory print head ink ejection function. The suction-based recovery is a recovery process during which a cap is employed to cover an ejection port face of the print head, wherein ejection ports are formed at the distal ends of ink nozzles (capping), and a suction force is applied to an inside of the cap to move viscous ink, for example, from the nozzles into the cap. The preliminary ejection process is a recovery process during which ink that does not contribute to the printing of an image is ejected through the nozzles of the print head into the cap.
When at a high temperature the print head is covered with the cap, air in the cap becomes inflated, and forces ink in the nozzles backward toward the print head, and thus, meniscuses of ink at the ejection ports of the nozzles may become unstable. In order to remove the inflated air from the inside of the cap, an air release port (atmospheric communication portion) is provided for the cap to release the air from the cap to the atmosphere. In Japanese Patent Laid-Open No. H05-104730(1993), a method is proposed for opening or closing the atmospheric communication portion in accordance with the temperature of the print head.
However, in a case where air in the cap that covers the print head becomes inflated, ink in the cap may be pushed outward to the atmospheric communication portion, and may, moreover, leak outside. Furthermore, in a case where the amount of ink in the cap has been increased, and where ink ejected into the cap for the preliminary ejection has splashed, some ink may enter the atmospheric communication portion, and may also, via the atmospheric communication portion, leak outside.
In Japanese Patent Laid-Open No. H05-104730(1993), no description is provided for the leakage of ink from the atmospheric communication portion to the outside, and a method for coping with such a leakage is not proposed.